HK1076668B - Method and apparatus for high rate packet data and low delay data transmissions - Google Patents

Description

Method and apparatus for high rate packet data and low latency data transmission

Reference to related, co-pending patent application

The present invention relates to the following U.S. patent applications:

U.S. patent application 08/963,386 entitled "method and apparatus for high rate packet data Transmission," filed on 1997, 3/11, and assigned to the present assignee, and incorporated herein by reference; and

U.S. patent application 09/697,372, entitled "method and apparatus for determining data rate in a high rate packet data wireless communication system," filed concurrently herewith and assigned to the present assignee is hereby incorporated by reference.

FIELD

The present invention relates to wireless data communication. More particularly, the present invention relates to a new and improved method and apparatus for high rate packet data and low latency data transmission in a wireless communication system.

Background

The growth in demand for wireless data transmission and the expansion of services achieved through wireless communication technologies have led to the development of special data services. One such service is referred to as "High Data Rate (HDR)". An exemplary HDR-type system is set forth in the TL90-54421-1 HDR air interface specification, also referred to as the HAI specification. HDR generally provides an efficient method of transmitting packet data in a wireless communication system. Difficulties arise in applications requiring both voice and packet data services. Voice systems are considered low latency data systems because voice communications are interactive and therefore processed in real time. Other low latency data systems include voice, multimedia and other real time data systems. HDR systems are not designed for voice communications, but are used to optimize data transmission because a base station propagates information through each mobile user and only sends data to one mobile user at a time. The propagation of information introduces time delays. Such delays can be tolerated for data transmission, since the information is not applied in real time. In contrast, for voice communications, propagation delay is unacceptable.

There is a need for a combined system for communicating high speed packet data information as well as low latency data, such as voice information. In such combined systems, there is a further need for a method of determining the data rate of a high rate packet data transmission.

SUMMARY

The disclosed embodiments provide a new and improved method for high rate packet data and low latency data transmission in a wireless communication system. In one embodiment, a base station in a wireless communication system first sets low-latency data, effectively as high priority, and then schedules packet data services at available power after the low-latency data is satisfied. Packet data services transmit packet data to a mobile user at a certain time. Another embodiment provides packet data to multiple mobile users at a time, allocating useful power among the multiple users. At a given time, one user is selected as the target recipient based on the channel quality. The base station determines the ratio of the useful power to the pilot channel power and provides this ratio to the selected mobile users. This ratio is also referred to as the "traffic-to-pilot" ratio, or "T/P" ratio. The mobile user uses the ratio to calculate the data rate and sends this information back to the base station.

In one example, the base station provides a "broadcast-to-pilot" ratio, or "B/P" ratio, to the mobile users, where this ratio takes into account the broadcast power, i.e., the total available transmission power of the base station, and the pilot power, i.e., the power fraction of the broadcast power used for the pilot channel. The mobile user determines a normalized data rate requested from the base station, where the normalized data rate is a function of B/P. The normalized data rate is sent to the base station and a decision is made as to the appropriate data rate. The selected data rate is transmitted to the mobile user.

In an illustrative example, parallel signaling channels are used to provide T/P ratio information to mobile users. This parallel signaling channel may be implemented using separate carrier frequencies, or by generating separate channels by any of a variety of methods.

According to another example, the T/P ratio is provided through a packet data information channel, wherein the T/P ratio is included in a header of a packet or is continuously provided together with packet data. Another example implements another metric based on the SNR of the pilot channel to estimate the SNR of the communication channel, wherein the metric is provided to the mobile user to determine the data rate. The mobile user requests transmission at or below a determined data rate. In one aspect, a wireless communication system operable to transmit packet data and low-latency data over a plurality of transmission channels includes a first set of channels within the plurality of transmission channels, the first set of channels being assigned for packet data transmission, the packet data being transmitted in frames; a second set of channels within the plurality of transmission channels, the second channels being assigned for low latency data transmission; a signaling channel within the plurality of transmission channels, the signaling channel assigned for transmission of information, wherein each information identifies a packet data intended recipient.

According to one aspect, in a wireless communication system supporting packet data transmission and low-latency data transmission on a plurality of transport channels, a method includes transmitting packet data over a set of packet data lanes; control information associated with the packet data is transmitted over a signaling channel, wherein the signaling channel is separated by groups of packet data channels. Wherein the control information identifies a target recipient of the associated packet data.

According to another aspect, a wireless device operable to receive packet data over at least one channel of a second set of channels, the wireless device comprising a processor operable to receive information over a signaling channel, and code information for determining target recipient information from the received information; the data rate determination unit is operative to calculate the data rate in accordance with the target recipient information and the encoding information.

Brief Description of Drawings

The features, objects, and advantages of the presently disclosed methods and apparatus will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein:

FIG. 1 illustrates in block diagram form one embodiment of a High Data Rate (HDR) protocol wireless communication system;

FIG. 2 shows a state diagram illustrating the operation of the HDR system as in FIG. 1;

FIG. 3 graphically illustrates usage scenarios of a plurality of packet data users within an HDR wireless communication system as in FIG. 1;

fig. 4 graphically illustrates power received by a user in an HDR wireless communication system, such as that of fig. 1.

FIG. 5 illustrates, in block diagram form, an HDR wireless communication system including low latency data users in accordance with one embodiment;

6-8 graphically illustrate power received by a user in an HDR wireless communication system, in accordance with various embodiments;

fig. 9 illustrates, in block diagram form, a portion of a receiver in an HDR wireless communication system in accordance with an embodiment;

fig. 10 illustrates, in flow diagram form, a method of processing traffic data in a wireless communication system employing signaling channels in accordance with an embodiment; and

fig. 11 illustrates, in flow diagram form, a method of determining a data rate for transmission in a wireless communication system in accordance with one embodiment.

Detailed description of the preferred embodiments

Although it is preferable to implement high rate packet data services and low latency voice type services in a system, this is a difficult task due to the large difference between voice services and data services. In particular, voice services have stringent and pre-specified latency requirements. The total one-way delay of a typical voice frame must be less than 100 ms. Data delay can be a variable parameter used to optimize the efficiency of a data communication system as compared to voice. There is a variation in time according to the channel condition given to the user, so it is possible to select a preferred time for transmitting the packet information according to the channel condition.

Yet another difference between voice and data services relates to the fact that voice services require a fixed and common level of service for all users. For example, in digital systems, GOS (grade of service) requires a fixed and equal transmission rate with a delay not greater than the maximum tolerable value of the Frame Error Rate (FER) of voice frames for all users. In contrast, for data services, GOS is not fixed, but varies from user to user. For data services, GOS is a parameter optimized to improve the overall efficiency of the data communication system. The GOS of a data communication system is generally defined as a predetermined amount of data, hereinafter referred to as the total delay occurring in packet transfer.

Yet another significant difference between voice services and data services is that the former requires a reliable communication link, which in the exemplary CDMA communication system is provided by soft handoff. Soft handoff may form redundant transmissions from 2 or more base stations in order to provide reliability. However, this increased reliability is not needed for data transmission, since erroneously received data packets can be retransmitted. For data services, the transmit power used to support soft handoff may be more efficiently used to transmit additional data.

High data rate data communications are typically transmitted using packet-switched techniques rather than circuit-switched techniques, as compared to voice and other low-latency data communications. The data is grouped into batches, with control information appended as headers and/or trailers. The combination of data and control information forms a packet. Various delays are introduced when packet data is transmitted through the system, even including the loss of one or more portions. HDR and other packet data systems generally tolerate time varying delays for packet data and lost packet data. This makes it possible to study the delay tolerance of the packet data system by scheduling transmissions with optimal channel conditions. In one embodiment, transmissions to multiple users are scheduled based on the quality of each transmission link. The transmission uses all of the available power at one time to transmit data to one of the plurality of users. This introduces variable delay because the multiple users do not know the intended recipient, transmission schedule, data rate and/or configuration information in advance, including modulation techniques, channel coding, etc. In one embodiment, instead of each receiver evaluating such information, the receiver requests the data rate and corresponding configuration. The schedule is determined by a scheduling algorithm and sent in synchronization information.

Before requesting a data rate, the receiver determines an optimal data rate, where the data rate may be based on the transmission power being used. The data rate is proportional to the transmission power and the channel quality. One combined system as used herein is a system that can handle both low-latency data and packet data transmissions. In a combined system capable of handling both voice and packet data transmissions, the available power and the available data rate vary with voice activity over time. The receiver is not aware of the voice activity of the system in determining the data rate. An example of a combined system is "wideband code division multiple access," such as the ANSI J-STD-01 recommendation for the W-CDMA (wideband code division multiple access) air interface compatibility standard for 1.85 to 1.99GHz Personal Communication Services (PCS), also known as "W-CDMA". Other systems include the "TIA/EIA/IS-2000 standard for CDMA2000 spread spectrum systems, also known as the" CDMA2000 standard "or other per-user connected systems.

A packet data system 20 that conforms to the protocol defined by the HAI specification is shown in fig. 1. In this system 20, base stations communicate with mobile stations 20 through 28. Each mobile station 26-28 is identified by an index value of 0 through N, which is the total number of mobile stations in system 20. The packet data channel 24 is shown as 1 multiplexer illustrating the exchangeable connections. The base station 22 may also be referred to as an "access terminal device" that provides user connectivity, particularly 1 user at a time. Note that access terminals are typically connected to a computing device such as a laptop computer or personal digital assistant. The access terminal may also be a cellular telephone with Web access capability. Meanwhile, the packet data channel 24 may also specify an "access network" providing a data connection between the packet switched data network and the access terminal device. In one example, the base station 22 connects the mobile stations 26-28 to the Internet.

In a typical HDR system, packet data communication is conducted in one link to a selected recipient, where a packet data channel 24 schedules a plurality of mobile stations 26-28, one at a time. The forward communication channel refers to data being transmitted from the base station, and the reverse communication channel refers to data being transmitted from the mobile stations 26-28. Packet data system 20 schedules users by implementing a link to one user at a given time. This is in contrast to a low latency data transmission system where multiple links are maintained simultaneously. The use of a single link allows the selected link to use a higher data transmission rate and to optimize transmission by optimizing the channel conditions for at least one link. Ideally, the base station uses only one channel when the channel is in the best condition.

Users of mobile stations 26-28 desiring data services provide a forward communication channel to base station 22 via a Data Rate Control (DRC) channel. The users are scheduled according to the quality of the received signal, wherein the scheduling is to ensure that the users are scheduled according to a fair criterion. For example, fair criteria may prevent the system from biasing toward mobile stations that are closer to the base station than mobile users that are farther away. The requested data rate is based on the received signal quality at the scheduled user. A carrier-to-interference ratio (C/I) is measured and used to determine a data rate of the communication.

Fig. 2 shows a state diagram illustrating operation of the system 20 of fig. 1, such as HDR system operation in compliance with the HAI specification. This state diagram illustrates the operation with a mobile subscriber MSi. In state 30, labeled "INIT," the base station 22 may access the packet data channel 24. During this state, initialization includes acquiring the forward pilot channel and synchronization control. Upon completion of initialization, operation moves to state 32, labeled "IDLE". In the space state, the connection to the user is closed and the packet data channel 24 awaits a command to open the connection further. When the mobile station MSi is scheduling, operation moves to state 34, labeled "TRANSMIT" (Transmit). In state 34, transmissions are made with MSi, where MSi uses the reverse traffic channel and base station 22 uses the forward traffic channel. If the transfer or connection fails, or the transfer terminates, then operation returns to the "IDLE" state 32. If another user within a mobile station 26-28 is scheduled, the transmission will terminate. If a new user MSj is scheduled outside of the mobile stations 26-28, the operation returns to the INIT state 30 to establish the connection. In this way, the system can schedule users 26-28 as well as users connected through additional access networks.

Scheduling users may optimize the service of system 20 to mobile stations 26-28 through multi-user diversity. An example of a usage pattern relating to 3 mobile stations MSO, MSi and MSN within the mobile stations 26-29 is shown in fig. 3. The power received by each user (in decibels) is plotted as a function of time. At time t1, MSN receives a strong signal, whereas MSO and MSi receive signals that are not so strong. At time t2, MSi receives the strongest signal, and at time t3, MSN receives the strongest signal. Thus, system 20 is able to schedule communications with MSNs around time t1, communicate with MSi around time t2, and communicate with MSOs around time t 3. The base station determines the scheduling based at least in part on the DRCs received from each mobile station 26-28.

An exemplary HDR transmission within system 20 is shown in fig. 4. Pilot channel transmission is promiscuous with packet data channels. For example, the pilot channel uses all of the useful power from time t0 to t1, also from time t2 to t 3. The packet data channel uses all of the useful power from time t1 to t2 and from time t3 and so on. Each mobile station 26-28 calculates the data rate based on the total available power as utilized by the pilot channel. The data rate is proportional to the useful power. This pilot channel accurately reflects useful power calculations when packet data system 20 is transmitting packet data to mobile stations 26-28. However, when voice and other low latency data services are coupled in a wireless communication system, the calculations are more complex.

Fig. 5 illustrates a CDMA wireless communication system 50 in accordance with one embodiment. The base station 52 communicates with a plurality of mobile users and uses services including, but not limited to, low latency data services only such as voice services, low latency data and packet data services and/or packet data services only. The system implements a cdma2000 compatibility protocol for packet data transmission services while also operating with low latency data services. At a given time, mobile stations 58 and 60(MS1 and MS2) use only packet data services, while mobile station 62(MS4) uses only voice services. The base station 52 maintains a communication link with the MS 462 via forward and reverse channels 72 and with the MSs 3, 56 via forward and reverse communications 70. For HDR communications, the base station 52 schedules users for data communications over a packet data channel 54. The HDR is also shown communicating with MSs 3, 56 over channel 64, MSs 1, 58 over channel 66, and MS 260 over channel 68. The users of each packet data service provide data rate information to the base station 52 on their respective DRCs. In one embodiment, the system 50 schedules a packet of data for a given time period. While in other embodiments multiple links are scheduled simultaneously, wherein each link uses only a portion of the available power.

The operation of the system 50 is illustrated in fig. 6, according to one embodiment. The pilot channel is continuously provided, which is a typical low latency data system. The power employed by the low-latency data channel varies over time and in accordance with the particular communication when the transmission is initiated, processed, and terminated. The packet data channel may use useful power after both the pilot channel and the low latency data service are satisfied. The packet data channel, also known as a "stored supplemental channel (PSCH)", includes system resources available after dedicated and shared channel allocations. As shown in fig. 6, the allocation of dynamic data involves storing all dedicated power and spreading codes, e.g., walsh codes, to form the PSCH. The maximum achievable propagation power for the PSCH is I_ormax。

According to one embodiment, the PSCH channel format defines parallel subchannels, each subchannel having a unique spreading code. One frame of data is then encoded, interleaved, and modulated. The resulting signal is demultiplexed on the subchannels. At the receiver, the signals are added together to reconstruct the frame. Variable frame length coding schemes may provide longer frames at lower frame rates/per time period. Each encoded packet is fragmented into subpackets, where each subpacket is transmitted over one or more time periods, providing incremental redundancy.

Compared to fig. 4, with HDR transmission, adding low latency data introduces a variable level for measuring the available power. In particular, in a packet data only system, all spreading codes, such as walsh codes, may be applied on the selected transmission link, as shown in fig. 4. When a voice or low-latency data service is added to a packet data service, the number of available codes becomes variable, varying with time. As the number of voice and low latency data services changes, the number of codes used to transmit the data also changes.

As shown in fig. 6, MS1 is scheduled during the period from t0 to t1, and MS2 is scheduled from t1 to t 2. During the time from t2 to t3, data links of multiple packets are connected, including MS1, MS3, and MS 4. During the time from t3 to t4, only MS1 is scheduled again. As shown, the power that the low latency data channel can consume varies throughout the time period t0 to t4, affecting the power available for packet data communications. When each mobile station calculates a data rate before receiving a transmission, a problem arises in the transmission if the available power is reduced without a corresponding change in the data rate. To provide the mobile stations 56-60 with up-to-date information about the available power, the base station 52 determines the ratio of the available power to the pilot channel power. This ratio is also known as the "traffic-to-pilot ratio", or "T/P" ratio. The base station 52 provides this ratio to the scheduled mobile stations 56-60. The mobile stations 56-60 use the T/P ratio, along with the SNR of the pilot channel, referred to herein as the "pilot SNR," to determine the data rate. In one embodiment, the pilot SNR is adjusted according to the T/P ratio to calculate a "traffic SNR," where the traffic SNR is related to the data rate. The mobile stations 56-60 then transmit the data rates back to the base station 52 as a request for DRC data rates.

In one embodiment, the T/P ratio is included in the header of the packet data or punctured into or inserted into the high rate packet data channel between packet data communications. As shown in fig. 7, the T/P ratio information is transmitted before the traffic and provides the mobile stations 56-60 with correction information regarding the available power as a result of the low latency data channel variations. Such variations also affect the number of codes, e.g., walsh codes, used to spread the information signal. Useful power reduction and code reduction, with a consequent reduction in data rate. For example, in one embodiment, if there are multiple packet data links, the packet data for a given user or all users is transmitted on channels corresponding to walsh codes 16-19 in a CDMA system.

In one exemplary embodiment shown in fig. 8, the T/P ratio information is provided to the mobile user using a parallel signaling channel. The parallel signaling channel is a low rate channel carried by independent walsh codes. This parallel signaling channel conveys the channel used for traffic and the type of coding employed to the intended recipient. The parallel signaling channels may be implemented using separate carrier frequencies, or by any of a number of methods that may form separate channels.

Note that packet data for a particular user is transmitted on 1 or more pre-selected channels. For example, in one embodiment of a CDMA wireless communication system, walsh codes 16 through 19 are assigned to data communications. In the exemplary embodiment shown in fig. 8, the signaling information is transmitted on a separate channel having a low transmission rate. The signaling information may be sent simultaneously with the data packet. The signaling information indicates the intended recipient of the data packet, the transmission channel of the data packet, and the encoding employed. The signaling information may be time-multiplexed into the high-rate data using separate walsh codes, or by puncturing or insertion.

In one embodiment, the signaling information is encoded as a frame, such as a header, that is shorter than the packet frame, allowing the receiver to decode the signaling information and make corresponding processing decisions. Received data that may be intended for the receiver is buffered awaiting a processing decision. If the receiver is not the intended recipient of the data, the receiver discards the buffered data, or interrupts all processing of the data, e.g., buffering, etc. If the signaling channel does not contain the receiver's data, the receiver discards the buffer and the receiver decodes the buffered data using the parameters indicated in the signaling information, reducing any standby time of the system.

In one embodiment, parallel signaling channels are transmitted to multiple users. Since a plurality of users can distinguish data arriving at the respective users, the respective users among the plurality of users can also receive common packet data. Thus, by providing this configuration information via signaling information, each user can retrieve and decode this packet data. In an embodiment, a message is transmitted to a plurality of users, wherein a group identifier is also transmitted. The group identifier is known a priori by the mobile users belonging to the group. This group identifier is placed in the header of the message. The group identifier may be a unique walsh code or other means of identifying the group. In one embodiment, the mobile user may belong to multiple groups.

Fig. 9 shows a portion of a mobile station 80 adapted for packet data services within system 50. The T/P ratio information is provided to the T/P processor 82. The pilot signal is provided to an SNR measurement unit 84 to calculate the SNR of the received pilot signal. The outputs of the T/P ratio and the pilot SNR are provided to multiplier 86 to determine the information SNR. This information SNR is then provided to a data rate correlator 88, which correlator 88 performs an adaptive transformation from the traffic SNR to a correlated data rate. The data rate correlator 88 then generates the data rate for transmission over the DRC. The functions performed by this portion of mobile station 80 may be implemented in dedicated hardware, software, firmware, or combinations thereof.

The T/P ratio may be transmitted using parallel signaling channels, as shown in fig. 8. The signaling information does not include the data rate because the receiver will determine the data rate from the T/P ratio. The receiver then determines the data arrival time based on the transmitted synchronization information. The signaling information is transmitted in parallel with the data. In another example, signaling information is punctured into the data.

Fig. 10 illustrates a method 100 for processing data in a wireless communication system capable of a combination of both packet data and low-latency data transmissions, according to an embodiment. The mobile station receives an information frame, which is received over an information channel, step 102. This frame of information is buffered at step 104. Buffering allows the mobile station to process this information at a later time without losing the transmitted data. E.g., buffering received data while additional processing is performed. Or in this example, data buffering delay processing until the mobile station determines the intended recipient of the data. The data targeted for the other mobile stations is disregarded and rather ignored to save valuable processing power. This buffered data is available for retrieval and processing when the mobile station confirms itself as the intended recipient. The buffered data represents received samples of the radio frequency. Other examples may determine the data rate of the transmission without buffering the information, wherein the received information is processed without first being stored in a buffer.

With continued reference to fig. 10, at step 104, the mobile station decodes recipient information regarding the information frame. In decision block 108, the process determines whether a given mobile subscriber matches the target recipient. If there is no match, the process continues to step 110 to discard the buffered information frame. The process then returns to step 102 to receive the next information frame. If the mobile station user is a match with the target recipient, the traffic channel frame is decoded at step 112 and the process returns to step 102. The ability to decode a small portion of the transmission and avoid unnecessary decoding and processing increases the operating efficiency of the mobile user and reduces the associated power consumption.

Fig. 11 illustrates various methods of determining a data rate in a combined wireless communication system in accordance with one embodiment. In step 122, the mobile station receives signals over traffic and pilot channels. At step 124, the mobile station determines a "pilot SNR" from the received pilot signal. In this embodiment, the pilot signal is transmitted on a unique channel for the designated pilot transmission. In other examples, the pilot signal may be truncated into one or more transmission signals on one or more channels. In one embodiment, the pilot signal is transmitted at a predetermined frequency different from the frequency of the information channel. For packet data transmission, the base station and each mobile station determine the data rate for the transmission. In one embodiment, the base station determines the transmission rate and informs the mobile station. In another embodiment, the base station and the mobile station negotiate a data rate in which to provide information to each other. This decision block 126 separates the process flow according to the data rate decision made. If the mobile station makes a data rate determination, processing continues to step 136. If the mobile station has not made a data rate determination, processing continues to step 128.

In one embodiment, the method of determining a data rate includes negotiation of a mobile station and a base station. In the negotiation, the mobile station determines the maximum achievable data rate. If the mobile station is the only receiver of the base station, the maximum available data rate may represent the data rate. In this case, the total transmit power obtained from the base station is dedicated to the mobile station. As shown, the mobile station receives a propagation-to-pilot ratio, or B/P ratio, at step 128, the propagation power being the total transmit power of the base station. Pilot power is the power consumed by the pilot signal transmitted from the base station. The mobile station determines a normalized data rate as a function of the B/P ratio and the pilot SNR. If all of the propagated power is for data traffic for both the mobile user and the pilot signal, then the normalized data rate corresponds to the data rate requested by the mobile user, while other users in a system 50 such as that shown in fig. 5 are ignored. In other words the normalized data rate is the maximum achievable data rate. The normalized data rate is then transmitted to the base station via a Normalized Data Rate Channel (NDRC), step 132. The base station receives the NDRCs from each mobile station and determines a corresponding data rate for each mobile user. The data rate indicator is then transmitted to each mobile station in step 134. The process then continues to step 144 and the mobile station receives traffic at this data rate and finally returns to step 122.

The B/P ratio represents a constant that generally changes slowly over time. The base station knows the ratio of the total propagation power and the power used for the pilot channel. Further embodiments implement additional power indicators, such as using a mesoscopic representation of the energy of the transmitted signal, the spectral density of the signal power, and the like.

With continued reference to fig. 11, in another method of determining the data rate, the determination of the data rate is made by the mobile station. For this embodiment, the mobile station receives the information-to-pilot ratio, i.e., the T/P ratio, at step 136. In step 138, the mobile station uses this calculated pilot SNR to generate a "traffic SNR" by adjusting the pilot SNR by the power used for traffic transmission. In this example, the T/P ratio is used to adjust the pilot SNR. The communication SNR then reflects the estimated SNR of the traffic transmission using useful power. At step 140, the traffic SNR is correlated to the data rate. The traffic SNR may be related to a carrier-to-interference (C/I) ratio or other channel quality indicator. In one embodiment, a look-up table stores traffic SNRs and associated data rates. Then, at step 142, the data rate is provided as a request to the base station on a "data request channel" (DRC). Processing continues to step 144.

In another embodiment, the mobile station uses the received pilot signal to estimate the T/P ratio. The received pilot signal provides a channel estimate for decoding traffic information. Low pass filtering may be used to filter the noise component from the received pilot signal. The filtering provides an estimate of the received noise in the pilot signal. Then, based on the filtering result, the T/P ratio is estimated. As an example, consider the following system model:

for k-0, 1, … …, M-1 (1)

Wherein r is_k ^tAnd r_k ^pRespectively, traffic and pilot signals received at the mobile station. The channel gain c is complex. Noise associated with traffic and pilot is represented by n_k ⁱAnd n_k ^pAnd (4) showing. The aggregate power (lumped power) of the pilot and traffic is P and T, respectively. As has been described above, in the above-mentioned,andin which E_c ^tAnd E_c ^pRepresents the energy of each chip of the yw and pilot channels, respectively, and, where G_tAnd G_pIs the corresponding processing gain. Note that the noise n is due to orthogonality between different code channels, both with zero mean square and variance Nt_k ^tAnd n_k ^pAre considered to be separate. For the above system model, the estimate of the traffic-to-pilot ratio is given by:

(2)

the Maximum Likelihood (ML) estimate of the traffic-to-pilot ratio can be found using the following estimation:

(3)

after approximation, (3) is simplified as follows:

(4)

where the constellation is assumed to have a unit average power.

(3) The estimate in equations (4) and (4) may be difficult to estimate because of the data sequence s representing the transmitted signal_kIs included in the equation. However, these equations are presentedIs completely statistical and can be used in the design of T/P ratio estimation algorithm.

According to one embodiment, the algorithm for estimating the T/P ratio is first appliedEstimatingAnd from r_k ^pThe noise variance is estimated, and the algorithm then defines the estimation of the T/P ratio as follows:

(5)

wherein the estimate of (5) is asymptotically unbiased. Note that the best estimate considers the 1 st momentum (moment) of the test statistic, while the estimate plan of (5) estimates the 2 nd order momentum. While both methods form unbiased estimates, the 2 nd order momentum will generally introduce a larger estimated variance. It is also considered that the mobile station uses the special format of the flat-column mode (constellation) in advance, since the required data sequence is not available using the 1 st order momentum.

In another embodiment, the T/P ratio estimation algorithm utilizesTo estimateAnd obtaining an empirical probability density function (PDK). Note that to make M large enough, x_kCan be approximately considered as having an average Rs_kGaussian (c) in (d). Then, can be selected from x_kThe R estimate is extracted from the PDF. There are many ways in this respect to go from x_kR is estimated in PDK of (1). In extracting the traffic-to-pilot ratio from the PDF, several features are available. E.g. in higher order modulation associated with high SNR, x is set_kCombined into several groups. The central layout of these clusters is similar to s_kThe parallel mode of (2). The spacing of some of the parallel mode points is equal for M-PAM, M-QAM, and M-PSK. Note that the distribution of each cluster approximately follows a gaussian PDF. The symbols transmitted are substantially equal using source coding, e.g., compression and/or vocoding, channel coding, etc.

In the frequency or time domain, the algorithm proceeds. For frequency domain analysis, the points of the parallel pattern may be arranged at equal intervals, e.g., x_kThe group of PDFs of (a), indicates that the PDFs are periodic. This interval or period is then determined by frequency domain analysis. For example, by computing the DFT of the PDF function to generate a histogram, the algorithm finds the dominant period again. R is calculated from the dominant period and the period between 2 parallel mode points. For M-QAM, the two-dimensional PDF functions can be viewed as two independent one-dimensional functions. In addition, the characteristic of equal spacing may be employed in the time domain. For example, by calculating the autocorrelation function of the PDF, the position of the 1 st sidelobe immediately after zero offset can provide two close clustersEstimation of the average period between centers.

In yet another example, the N centers of the PDF groups are first found. For k 0, 1 … N-1, this method assumes that the center of the estimate is { d }_kAnd for k 0, 1 …, N-1, constellation points { a }_kAre of the same order. Using the least squares algorithm, the following R estimates can be generated

(6)

Note that the center of the PDF function may be determined by a variety of methods.

Because the constellation points are substantiallyEqual, the method first finds the cumulative probability function (CDF) from the PDF. Clustering is carried out by applying a threshold scheme to the CDF. The center of each group is then calculated by averaging within the group using the first order momentum. In further embodiments, a feature extraction technique may be employed as used in image processing, where, for example, the feature may be a peak or a molding (template) built on a gaussian PDF approximation. Note that image segmentation techniques such as clustering or region growing may provide a method to group points of the empirical PDF. Comparing (6) and (4), the similarity between the clustering process and the hard decoding is described, where the actual signal s in (4)_kIs a symbol a hard decoded by in (b)_mAnd (4) replacing.

In a typical HDR system, such as the system 20 shown in fig. 1, a link is established between base stations at a time. In one embodiment, a wireless communication system is extended to support multiple users at a time. In other words, system 50 of fig. 5 enables base station 52 to simultaneously transmit data to multiple data users of mobile units 56, 58, and 60. Note that while 3 mobile units are shown in fig. 5, any number of mobile units may be in communication with base station 52 within system 50. The expansion of multiple users provides for multiple communications over the packet data channel 54. At a given time, users that are supported by the packet data channel are referred to as "active receivers". Each working receiver decodes the signaling message to determine the T/P ratio of the packet data channel 54. Each working receiver handles the T/P ratio without regard to the potential capabilities of the other working receivers. The base station receives data rate requests from the operating receivers and allocates power proportionally.

Returning to fig. 1, in a conventional HDR communication system, much information is known in advance, including, but not limited to, constellation information, coding schemes, channel identification, and useful power for transmitting packet data. The constellation information refers to a modulation scheme by which digital data information is modulated onto a carrier for transmission. Modulation schemes include, but are not limited to, "binary phase shift keying," Quadrature Phase Shift Keying (QPSK), "quadrature amplitude transform (QAM)," and the like. Coding schemes have aspects of encoding the source information into digital form, including, but not limited to, "scrambling code encoding," "convolutional encoding," "error encoding," such as Cyclic Redundancy Check (CRC), rate setting, and the like. The receiver can request the constellation and the coding information through DRC. The channel identification includes, but is not limited to, spreading codes such as walsh codes in spread spectrum communication systems, and may include carrier frequencies. The channel identification may be determined in advance and fixed. The transmission power typically used for packet data transmission is known based on the known total useful transmit power and the known pilot signal power.

In a combined system of 1 packet data and low latency data, some of the above information is not known a priori, but rather the information is subject to variations in the useful power and useful channel shared with the low latency data, such as voice communications. A comparison is made in the following table.

Table 1 information available in HDR systems

	HDR	Combination of	Combination of
				Information	Packet data only	T/P	Signalling channel
Target recipient	Decoding data packets	Decoding data packets	Message
				Conformation	DRC	DRC	DRC
Encoding	DRC	DRC	DRc
				Channel with a plurality of channels	Fixed	Unknown	Message
Data traffic power	Fixed	T/P	Unknown

The use of a signaling channel, as shown in fig. 8, provides a receiver with a lot of information. This message identifies the intended recipient and the channel for packet data transmission. The DRC information requests the data rate, specifies the constellation and the coding. An available traffic power indicator is provided, wherein in one example, the indicator represents a ratio of available traffic power to pilot signal strength, which provides a measure of determining the data rate. According to one example employing separate parallel signaling channels, information regarding the intended recipient, constellation and coding is transmitted over the traffic channel and/or DRC while the traffic power regarding the data channel and data is transmitted over the parallel signaling channels.

The above embodiments and combined applications of the embodiments may combine packet data and low latency data transmission in a wireless communication system. As described above, the combination of voice and packet data introduces a variable number in the transmission. The use of separate signaling channels provides information to a receiver in a wireless communication system without degrading communication quality. The information of the signaling channel may identify target recipient information. Transmitting a useful communication indication to the receiver may provide assistance to the receiver in determining the data rate from the transmitter. Also, when the information indicator is used by multiple receivers, wherein each receiver calculates a data rate therefrom, the transmitter receives information that facilitates the transmitter in assigning a transmission channel for packet data transmission to the multiple receivers.

Thus, there has now been set forth a new and improved method and apparatus for high rate data transmission in a wireless communication system. Although a CDMA system is described in the exemplary embodiments discussed herein, the various embodiments are applicable to all methods of wireless per-user connection. The exemplary embodiment IS described with respect to HDR for an efficient communication system, but IS also applicable to IS-95, W-CDMA, IS-2000, GSM, TDMA, etc.

Those skilled in the art will appreciate that the data, instructions, commands, information, signals, data bits, symbols, and chips that may be referenced throughout the above description may be advantageously represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, algorithm steps, etc., described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. The various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system and how best to implement the recited functionality for each particular application.

As such, the various illustrative logical diagrams, modules, circuits, and algorithm steps described in connection with the examples disclosed herein may be implemented or performed with a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components such as registers and first-in-first-out type, a processor executing 1 set of firmware instructions, any conventional programmable software module and a processor, or any combination thereof designed to perform the functions described herein. The processor is preferably a microprocessor, but in the alternative, the processor may be a generally conventional processor, controller, microcontroller, or state machine. The software modules may reside in RAM, FLASH memory, ROM, electronically programmable ROM, electronically erasable programmable ROM, registers, hard disk, a removable disk, a compact disk ROM (CD-ROM), or any form of storage medium known in the art. The processor may reside in an ASIC (not shown). The ASIC may reside in the phone (not shown). A processor may be implemented as a combination of a DSP and a microprocessor or 2 microprocessors in conjunction with a DSP core.

The above description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other examples without the use of the inventive technique. Thus, the present invention is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (22)

1. A wireless communication system for transmitting packet data and low-latency data on a plurality of transmission channels, the system comprising:

a first set of channels in the plurality of transport channels, the first set of channels being allocated for packet data transmission and packet data being communicated in frames;

a second set of channels in the plurality of transport channels, the second set of channels being allocated for low latency data transmission; and

a signaling channel among the plurality of transport channels, the signaling channel being allocated for transmission of messages, wherein each message identifies a packet data intended recipient, and each message is transmitted simultaneously with a packet data frame.

2. The wireless communication system of claim 1, wherein a first message of the messages transmitted on the signaling channel is related to and transmitted concurrently with a first packet data frame of the packet data transmitted in frames in a first group of channels, and the first message identifies a first packet data intended recipient related to the first packet data frame.

3. The wireless communication system of claim 2, wherein the first message identifies a subset of the first set of channels allocated for transmission of a first packet data frame.

4. The wireless communication system of claim 2, wherein the first message identifies a coding scheme used for transmission of a first packet data frame.

5. A wireless device operating in the system of claim 1, the wireless device receiving packet data over at least one of the first set of channels and receiving messages over a signaling channel, the wireless device comprising:

a buffer for storing packet data received through the at least one channel of the first set of channels;

a processor coupled to the buffer to determine target recipient information based on the received message; and

a decoder coupled with the processor, the decoder decoding a received data packet if the wireless device is a target recipient and disregarding a data packet if the wireless device is not a target recipient.

6. The wireless apparatus of claim 5, wherein the target recipient information identifies a plurality of recipients.

7. The wireless device of claim 6, further comprising:

a memory storage device coupled to the processor for storing computer readable instructions for controlling the decoder.

8. In a wireless communication system, a method for supporting packet data transmissions and low-latency data transmissions on a plurality of transport channels, the method comprising:

receiving data requests from a plurality of mobile units;

determining a transmission schedule according to the data request;

assigning a priority to each of the plurality of mobile units;

determining a traffic schedule among the plurality of mobile units based on priorities, wherein a mobile unit given a high priority experiences less interference than other mobile units of the plurality of mobile units;

transmitting packet data through a set of packet data channels;

transmitting control information associated with the packet data over a signaling channel, wherein the signaling channel is separate from the group of packet data channels, and the control information identifies a target recipient of the associated packet data, a transmission channel for transmitting the packet data, and the control information further identifies a coding scheme for the packet data, wherein the control information is transmitted concurrently with the packet data.

9. A wireless device for receiving packet data over at least one channel of a first set of channels, the wireless device comprising:

a processor for receiving a message over a signaling channel and determining target recipient information and coding information from the received message, wherein the message is transmitted to the processor simultaneously with the packet data; and

a data rate determining unit for calculating a data rate of the packet data according to the target recipient information and the coding information.

10. The wireless apparatus of claim 9, wherein the wireless apparatus operates in a wireless communication system that supports high rate packet data transmissions and low latency data transmissions.

11. The wireless apparatus of claim 9, further comprising:

a buffer coupled to the processor to store packet data received over the at least one channel of the first set of channels;

a decoder coupled with the processor, the decoder decoding a received data packet if the wireless device is a target recipient and disregarding a data packet if the wireless device is not a target recipient.

12. The wireless apparatus of claim 9, wherein the target recipient information identifies a plurality of target recipients.

13. The wireless apparatus of claim 9, wherein the coding information is predetermined by a transmitter and used to code the packet data, and wherein

The wireless device also includes:

a decoder coupled to the processor, the decoder decoding received packet data in response to the encoded information.

14. A wireless communication system for transmitting packet data and low delay data on a plurality of transport channels, the system comprising:

a first set of channels in the plurality of transport channels, the first set of channels being allocated for packet data transmission and packet data being communicated in frames;

a second set of channels in the plurality of transport channels, the second set of channels being allocated for low latency data transmission; and

a signaling channel in the plurality of transport channels, the signaling channel being allocated for transmission of messages, wherein a message corresponds to a packet transmitted on one of the first set of channels, the message identifies parameters of the packet, and the message is transmitted concurrently with a packet data frame.

15. The wireless communication system of claim 14, wherein the message is transmitted on a reverse link from a mobile station to a base station.

16. The wireless communication system of claim 14, wherein the message is transmitted on a forward link from a base station to a mobile station.

17. The wireless communication system of claim 14, wherein the parameter comprises a traffic power indicator.

18. The wireless communication system of claim 14, wherein the parameters correspond to coding and modulation used in transmitting the packet.

19. A wireless device for processing packet data over at least one channel in a first set of channels and low-latency data transmissions over at least one channel in a second set of channels, the wireless device comprising:

means for processing data in frames on at least one channel of the first set of channels;

means for processing low-delay data on at least one channel in the second set of channels;

means for encoding a message corresponding to a particular packet and identifying parameters of the packet; and

means for transmitting the message on a signaling channel concurrently with the data in the form of frames.

20. A wireless device for transmitting or receiving packet data over at least one channel in a first set of channels and low-latency data over at least one channel in a second set of channels, the wireless device comprising:

means for processing packet data in frames on at least one channel of the first set of channels;

means for processing low-delay data on at least one channel in the second set of channels;

means for receiving a message corresponding to a specific packet on a signaling channel, wherein the message is transmitted simultaneously with the packet data in the form of frames;

means for decoding the message corresponding to the particular packet and identifying parameters of the packet; and

means for using the parameter in the reception of the particular packet.

21. A wireless device for receiving packet data over at least one channel of a first set of channels, the wireless device comprising:

a processor for receiving a message through a signaling channel and determining packet parameter information and coding information according to the received message, wherein the message and the packet data are simultaneously transmitted to the processor; and

a packet decoder for decoding the received message according to the packet parameter information and the coding information.

22. A wireless communications apparatus that supports packet data communications and low-delay data communications over a plurality of transport channels, the wireless communications apparatus comprising:

means for receiving packet data over a set of packet data channels;

means for receiving control information associated with the packet data over a signaling channel, wherein the signaling channel is separate from the group of packet data channels and the control information identifies a target recipient of the associated packet data, wherein the control information is transmitted concurrently with the packet data;

means for receiving data requests from a plurality of mobile units;

means for determining a transmission schedule in accordance with the data request;

means for assigning a priority to each of the plurality of mobile units;

means for determining traffic scheduling among the plurality of mobile units based on priority, wherein a mobile unit given a high priority experiences less interference than other mobile units of the plurality of mobile units.